1. Field of the Invention
The invention relates to a semiconductor processing system and to a method wherein light emanating from a light source is shielded from reaching a temperature detector.
2. Discussion of Related Art
Semiconductor devices are manufactured by locating a semiconductor wafer within respective semiconductor processing chambers and conducting respective processing steps on the wafer. A light source is usually positioned to heat the wafer when located within such the chamber. A temperature detector, such as a pyrometer, detects the temperature at a location within the chamber, such as on a surface of the wafer. It may be necessary to shield the temperature detector from light emanating from the light source so that an accurate temperature signal is received from the temperature detector. Such a signal may then be used for purposes of controlling power supplied to the light source.
Various components within the chamber serve to block light emanating from the light source. These components are made from different materials for different purposes. For example, the materials may have to be resistant to reaction with chlorine since chlorine is often used for cleaning such a semiconductor processing chamber. Not many materials comply with both effective light blocking characteristics and resistance to reaction with chlorine. Quartz is a material which is resistant to chlorine, although quartz is translucent and would therefore not comply with required light blocking characteristics. Wafer seats, usually provided within the semiconductor processing chamber, are often made from graphite which is covered by silicon carbide. Such a seat has both effective light blocking characteristics and resistance to reaction with chlorine.
A component, having magnetic characteristics, is also sometimes located within the semiconductor processing chamber for purposes of supplying movement to the wafer. The component may, for example, be a rotor which is linked to the wafer seat by means of a member so that rotational movement of the member causes the seat, and therefore the wafer, to rotate. Some materials which are used for such components lose their magnetic characteristics once they reach elevated temperatures, typically above 100.degree. C. Any member thus linking the wafer seat to the component is therefore required to have a low thermal conductivity in order to protect the component from heat which builds up at the seat. A material with low thermal conductivity is quartz although quartz, as mentioned, is translucent and would not comply with required light blocking characteristics.
A semiconductor processing system is thus required which includes a member shielding light, emanating from a light source, from reaching a temperature detector, wherein the member is also resistant to reaction with chlorine and preferably also has a low thermal conductivity.